Incinerator having afterburner grate

ABSTRACT

An incinerator has a combustion chamber which is at least partially surrounded by a housing. The combustion chamber has at least one ash outlet to which at least one afterburning grate for unincinerated components of the ash is assigned.

The present invention relates to an incinerator of the type of a carbon incinerator, refuse incinerator, a substitute fuel incinerator or a biomass incinerator.

In plants of the aforementioned type, fuels, for example coal or refuse, are regularly incinerated. To this end, the fuels are incinerated on a fuel grate within a combustion chamber of the incinerator. In known incinerators it has emerged that the ash of the fuels which is produced in this case is often unsuitable for further processing, for example in the production of cement, because the grain size of the ash does not exhibit the required size and/or the ash exhibits an excessively high fraction of unincinerated components.

It is therefore an object of the invention to at least partially solve the problems described with respect to the prior art and, in particular, to provide an incinerator with the aid of which combustion residue can be produced which has advantageous properties with respect to further processing. In addition, a method for incinerating fuels is to be indicated in which combustion residue is generated which has properties that are advantageous for further processing.

These objects are achieved by an incinerator as claimed in claim 1 and a method as claimed in claim 10. Further advantageous embodiments of the invention are indicated in the dependent claims. It is to be noted that the features which are individually indicated in the dependent claims may be combined with one another in any technologically meaningful manner and define further embodiments of the invention. Moreover, the features indicated in the claims will be rendered more precisely and explained in more detail in the description, with further preferred embodiments of the invention being presented.

The incinerator according to the invention has a combustion chamber which is at least partially surrounded by a housing, wherein the combustion chamber has at least one ash outlet to which at least one afterburning grate for unincinerated components of the ash is assigned.

In the combustion chamber of the incinerator, fuels, such as in particular lignite, bituminous coal, refuse and/or substitute fuels, for example plastics and/or old tires, are incinerated in order to release thermal energy. This thermal energy is extracted from the incineration emissions by means of heat exchangers (for example pipe packages) and, for example, fed to turbines for the conversion of thermal energy into electric power. To this end, the fuel is fed via a fuel duct to the combustion chamber, where the fuel is incinerated. The combustion chamber is at least partially surrounded by a housing which is equipped with pipes holding coolant water (heat exchangers) and/or at least partially with a fireproof cladding. Subsequent to the almost complete primary incineration of the fuel in the combustion chamber, the ash of the fuel with the unincinerated components of the fuel contained therein is removed from the combustion chamber via at least one ash outlet. The at least one ash outlet is in particular a (closable) opening in the combustion chamber floor, through which the ash can be removed from the combustion chamber. For this, a combustion chamber floor is configured with, for example, an incline in the direction of the at least one ash outlet, and/or in the combustion chamber fuel conveyors, for example movable gates and/or roller conveyors and/or plate conveyors and/or chain conveyors are located with which the fuel and/or the ash can be conveyed towards the at least one ash outlet. The at least one ash outlet is followed downstream by a duct and/or a funnel, through which the ash with the unincinerated components of the fuel can be removed from the combustion chamber with the aid of gravity. In order to minimize the fraction of unincinerated components of the ash, it is thus in other words proposed that at least one afterburning grate is located in the at least one ash outlet and/or in the duct and/or funnel which is/are contiguous to the at least one ash outlet. This, in particular, also means that this afterburning grate is still part of the incinerator, thus in a region extending up to the discharge point onto a downstream ash conveyor which is mounted below the ash outlet. The at least one afterburning grate is a horizontal and/or at least partially inclined plane on which the ash having the unincinerated components at least partially comes to lie for a certain duration. The at least one afterburning grate is, in particular, configured in the manner of a roller grate, infeed grate, reciprocating grate, flat grate, traveling grate and/or step grate and/or consists at least partially of (hollow) tubes, (hollow) beams and/or grills.

On account of gravity the ash falls through the at least one ash outlet onto the afterburning grate in the course of removing the ash from the combustion chamber, such that on account of the impact on the at least one afterburning grate the ash is at least partially reduced to small pieces and/or mixed through, and unincinerated components of the ash are released in this manner. To this end, the at least one afterburning grate is arranged such that the ash falls from a height of at least 1 meter, particularly preferably at least 2 meters, or most particularly preferably at least 3 meters from the combustion chamber onto the at least one afterburning grate. On the at least one afterburning grate the ash is subjected to an afterburning. This means, in particular, that the afterburning of the ash takes place at a temporal and/or physical distance from the (primary) incineration of the fuel in the combustion chamber and/or a reduction in the temperature of the ash takes place between the incineration in the combustion chamber and the afterburning on the at least one afterburning grate. For the purpose of afterburning the ash, the ash remains at least partially on the at least one afterburning grate until the unincinerated components of the ash have been reduced to a level which is advantageous for further processing of the ash. The permissible fraction of unincinerated components in the ash depends on the envisaged further processing of the ash and can be determined by a person skilled in the art by means of routine operations.

The combustion chamber preferably has at least one main incineration grate.

This main incineration grate at least partially forms the floor of the combustion chamber and is configured in the manner of a roller grate, infeed grate, reciprocating grate, flat grate, traveling grate and/or step grate. The at least one main incineration grate serves, in particular, in conveying the fuel through the combustion chamber, in particular toward the at least one ash outlet, and can, in particular, have passages for aerating the fuel on the main incineration grate.

It is likewise advantageous for the at least one afterburning grate to be rigidly connected to the at least one ash outlet, or to a duct or funnel which is contiguous to the at least one ash outlet. This means, in particular, that the unincinerated components of the ash can be incinerated essentially motionlessly, once they have come to lie on the at least one afterburning grate.

The at least one afterburning grate is preferably implemented with a cooling device. Here, this may, in particular, refer to an at least partial throughflow of a cooling medium through the at least one afterburning grate. In this manner, overheating of the at least one afterburning grate and thus damage can be prevented. In this manner, in the case, for example, of a direct firing in the region of the afterburning grate, it is also possible for the temperature of the (at least partially solidified) ash which has been conveyed onward to be influenced or set and/or for the air flow passing there to be influenced or set with respect to temperature.

It is particularly advantageous for at least one burner to be located adjacent to the at least one afterburning grate. This at least one burner is preferably operated with oil and/or gas and in particular serves in igniting unincinerated components of the ash on the at least one afterburning grate and in supporting the afterburning of the ash. On account of this, the fraction of unincinerated components in the ash can be actively controlled in a particularly advantageous manner.

It is likewise advantageous for the at least one afterburning grate to be followed downstream by an ash conveyor which has a further incineration zone. This means, in particular, that the ash which is conveyed by the ash conveyor is further incinerated on the ash conveyor and thus the fraction of unincinerated components in the ash is reduced even further. In this manner, a very compact and complete incineration of the fuel is made possible besides the primary incineration in the combustion chamber, the secondary incineration in the region of the afterburning grate, and a tertiary incineration in the ash conveyor, even in the case of fuels which are classified as being slow-burning. At the same time, the available space is used highly efficiently and the effectiveness of the incinerator is considerably improved. To this end, openings may be located in the ash conveyor, through which afterburning air can flow at least partially through the ash.

The position of the at least one afterburning grate is preferably adjustable. This means, in particular, that the at least one afterburning grate in the ash outlet and/or in the duct and/or funnel which is/are contiguous to the at least one ash outlet is at least partially height-adjustable and/or, for the at least partial removal of the ash from the at least one afterburning grate, can be at least partially pivoted and/or turned.

According to a further expedient embodiment, the at least one main incineration grate has first passages or the at least one afterburning grate has second passages, wherein a size of the first passages or a size of the second passages is adjustable. The first passages and/or second passages serve, in particular, in enabling the throughflow of (combustion) gas, in particular oxygen, through the fuel and/or the ash. Beyond this, the first passages and/or second passages serve in removing fuels and/or ash from the combustion chamber and/or the at least one ash outlet. On account of the adjustability of the size of the first passages and/or second passages it can be ensured that the ash can only fall through the at least one main incineration grate and/or at least one afterburning grate through the first passages and/or second passages once it has been incinerated to the extent that a grain size arises which is smaller than the size of the first passages and/or second passages. Beyond this, the adjustment of the size of the first passages and/or the adjustment of the size of the second passages can also serve in controlling an amount of oxygen which flows through the at least one main incineration grate and/or afterburning grate through the fuels and/or ash and/or into the combustion chamber.

Preferably, the size of the first passages is larger than the size of the second passages. Via the size of the first passages, a desired degree of preliminary incineration, which is particularly suitable for subsequent afterburning, can be set in this case.

Pursuant to a further aspect of the invention, a method for the incineration of fuels is also proposed, which has at least the following steps:

-   -   a) providing fuel in a combustion chamber;     -   b) at least partially incinerating the fuel in the combustion         chamber to form ash;     -   c) conveying the at least partially incinerated fuel and the ash         to at least one afterburning grate which is assigned to an ash         outlet of the combustion chamber;     -   d) afterburning the at least partially incinerated fuel on the         at least one afterburning grate.

It has to be clarified that this method for the incineration of fuels is provided, in particular, for the incineration of fuels in an incinerator according to the invention.

Accordingly, reference is made here to the description of the incinerator according to the invention.

According to a preferred development of the method it is also provided that subsequently a step e) is carried out, wherein the ash is then deposited onto an ash conveyor.

It is also viewed advantageously that, following step e), a simultaneous afterburning and cooling of the ash in the ash conveyor takes place during conveying, wherein particularly preferably ambient air is brought into contact in a counter-flowing manner with the ash.

The invention and also the technical background are described in more detail in the following by means of the FIGURE. It should be mentioned that the FIGURE shows a particularly preferred variant of an embodiment of the invention, but that said invention is not limited to said variant of an embodiment. In a schematic illustration:

FIG. 1: shows an incinerator according to the invention.

FIG. 1 shows an incinerator 1 having a combustion chamber 2. The combustion chamber 2 is at least partially surrounded by a housing 3 and a combustion chamber floor 19. Fuel 14 is filled into the combustion chamber 2 via a fuel funnel 20 and a fuel duct 15. In the present exemplary embodiment, at the exit of the fuel duct 15, the fuel 14 is conveyed through the combustion chamber 2 by means of a fuel conveyor 16 which is at least vertically movable. In the combustion chamber 2, the fuel 14 is incinerated at least partially to form ash 6. The incineration emissions generated here rise upward in the combustion chamber 2 and flow through empty passes 17 of the incinerator 1 to pipe packages 18 which channel the thermal energy of the combustion gases to turbines which are not shown here. The combustion chamber floor 19 is at least partially configured with a main incineration grate 7 which has first passages 12. The first passages 12 can be adjusted in their size and/or completely closed off and serve, in particular, in aerating the fuel 14 on the main incineration grate 7. Fuel 14 and/or ash 6 which fall through the first passages 12 can be conveyed away toward a duct 23 and funnel 22 by a conveyor situated below said main incineration grate 7. Beyond this, the combustion chamber 2 has an ash outlet 4, under which the duct 23 extends up to the funnel 22. The ash 6 is conveyed by the fuel conveyor 16 into the ash outlet 4 through which the ash 6 falls from a height 21 through the duct 23 onto an afterburning grate 5. An afterburning of unincinerated components of the ash 6 takes place on the afterburning grate 5, such that the fraction of unincinerated components of the ash 6 is reduced. For aiding this afterburning, a burner 9 is located in the region of the afterburning grate 5. In order to prevent overheating of the afterburning grate 5, a cooling media with the aid of a cooling device 8, schematically indicated here as dashed arrows, flows through said afterburning grate 5. The afterburning grate 5 in addition has second passages 13, the size of which is adjustable. The afterburnt ash falls through the second passages onto an ash conveyor 10 which is situated below, said ash conveyor 10 along its conveying path being configured as an afterburning zone 11 in which the unincinerated components of the afterburnt ash 6 are further reduced. In order to be able to remove from the afterburning grate 5 ash particles having a larger diameter than the second passages 13, the afterburning grate 5 is pivotable about an axis not shown here.

The incinerator according to the invention and the method according to the invention for the incineration of fuels distinguish themselves in that the ashes produced in this manner have a particularly low fraction of unincinerated components and are thus particularly suitable for further processing.

LIST OF REFERENCE SIGNS

1 incinerator

2 combustion chamber

3 housing

4 ash outlet

5 afterburning grate

6 ash

7 main incineration grate

8 cooling device

9 burner

10 ash conveyor

11 afterburning zone

12 first passages

13 second passages

14 fuel

15 fuel duct

16 fuel conveyor

17 empty passes

18 pipe packages

19 combustion chamber floor

20 fuel funnel

21 height

22 funnel

23 duct 

1. Incinerator having a combustion chamber which is at least partially surrounded by a housing, wherein the combustion chamber has at least one ash outlet to which at least one afterburning grate for unincinerated components of the ash is assigned.
 2. Incinerator as claimed in claim 1, wherein the combustion chamber has at least one main incineration grate.
 3. Incinerator as claimed in claim 1, wherein the at least one afterburning grate is rigidly connected to the at least one ash outlet, or to a duct or funnel which is contiguous to the at least one ash outlet.
 4. Incinerator as claimed in claim 1, wherein the at least one afterburning grate is implemented with a cooling device.
 5. Incinerator as claimed in claim 1, wherein at least one burner is located adjacent to the at least one afterburning grate.
 6. Incinerator as claimed in claim 1, wherein the afterburning grate is followed downstream by an ash conveyor which has a further afterburning zone.
 7. Incinerator as claimed in claim 1, wherein the position of the at least one afterburning grate is adjustable.
 8. Incinerator as claimed claim 7, wherein the at least one main incineration grate has first passages or the at least one afterburning grate has second passages, wherein a size of the first passages or a size of the second passages is adjustable.
 9. Incinerator as claimed in claim 8, wherein the size of the first passages is larger than a second size of the second passages.
 10. Method for the incineration of fuels having at least the following steps: a) providing fuel in a combustion chamber; b) at least partially incinerating the fuel in the combustion chamber to form ash; c) conveying the at least partially incinerated fuel and the ash to at least one afterburning grate which is assigned to an ash outlet of the combustion chamber; d) afterburning the at least partially incinerated fuel on the at least one afterburning grate.
 11. Incinerator as claimed in claim 2, wherein the at least one main incineration grate has first passages and the at least one afterburning grate has second passages, wherein a size of the first passages or a size of the second passages is adjustable.
 12. Incinerator as claimed in claim 11, wherein the size of the first passages is larger than a second size of the second passages. 